Mobility is one of the most valuable features of contextual HMIs for engineers and operators. A workstation HMI usually employs a web browser but with contextual HMIs, the difficulty in browsing a much bigger screen on a mobile device is eliminated. By definition, contextual HMIs mean that the display is adjusted according to the worker’s device specification, fitting the need of the work that needs to be performed.
The specific HMI components that are displayed on the operator’s display are pushed to his/her device through a contextual mobility server, which is aware of the user’s location and accessibility level. This happens only when the worker is within a specified range of the device that needs to be maintained/set-up. For security reasons, it is imperative that the device be automatically removed from the HMI service after a certain time-frame or proximity level.
A plant manager can take full advantage of contextual HMIs when the deployed infrastructure isn’t studded with complexities. Mobile devices sit at the core of contextual HMI infrastructure. With advancement in mobile technologies, geo-location and wireless connectivity is affordably available in devices, making it feasible to provide a dynamic and contextual HMI based on the worker’s proximity to a geographical area. The definition of a “geographical area” is vague and is up to the facility managers; a zone can be a room, a floor or the entire facility, or it may be just a few meters around the device in question.
Geographical zones can be designed with the help of geo-tags such as near-field communications (NFC), Bluetooth low energy beacons (iBeacons) or QR codes, which are then placed strategically around assets to elicit contextual HMI push to mobile devices. Next, a secure proximity services mobile application needs to be developed that receives identification from the geo-tags whenever the zone’s range is breached. If more than one device needs to be used within a specific range, then a geo-tag with a stronger signal is needed. The concept is termed as “geo-fencing”, allowing control actions to take place based on the zone the operator is in.
The order of operation is as follows:
It should be noted that neither the contextual mobility server nor the mobile app communicates directly with the asset. The role of monitoring, control and automation remains with the Supervisory Control and Data Acquisition (SCADA) or Building Management System (BMS), with the contextual mobility server acting as an intermediate. It receives inputs from the mobile device which it then relays to the SCADA/BMS using OPC or other compatible protocols.
The entire infrastructure rests on two technologies:
The mobility server is responsible for maintaining a database that keeps track of the geo-zones, user profiles and information regarding the equipment controls, actions and events. The Contextual Logic Engine carries out all authentications and generates appropriate actions for the distribution of information to the mobile device. This may include resources such as schematics, drawings, etc. that the operators need to fulfill their task.
Through Contextual HMIs, operators and maintenance personnel are able to get their tasks done more effectively, through greater situational awareness and intelligent control. Required information is posted to the mobile device automatically whenever the server detects the user has entered the geo-zone and all authentication procedures have been satisfied. This eliminates the need for having an HMI designed for the asset, along with the hassle of installing a monitor screen that will ultimately be in an unsuitable location. When a fault occurs, the nearest technician can be called, requiring nothing but his/her mobile device to carry out troubleshooting. In contrast, maintenance can get tricky if the HMI screen itself is damaged during an accident.
The contextual mobility infrastructure would be incomplete without a private and most importantly secure messaging system, as it allows operators to exchange information with each as well as the control room. The functionalities of the messaging system don’t need to be advanced, but should at least include text, photos, videos and audio communication.
An integrated messaging system is more useful than third-party software as it boosts productivity. Users don’t need to switch screens or worry about disclosing confidential information, and the messages can become a permanent part of the Operations & Maintenance record. All this is not possible with third-party apps. Furthermore, electronic messaging allows messages to be directed within specified access groups or individuals, which can in turn be supervised by the plant manager.
A contextual mobility infrastructure would only be successful if mobile devices have access to the network in all locations. Poor signal strength may lead to interruption or sluggishness that would defeat the purpose of contextual HMIs. Therefore, in addition to effective placement of geo-tags, the design should incorporate the work load a particular asset will encounter, choosing the network infrastructure’s capabilities accordingly.
Lastly, the high cost of deploying a contextual HMI solution may be a hindering factor, however, the long-term benefits, such as, elimination of stationary HMIs, boosted productivity and improved safety, will offset the advantage.